Life History Evolution in Plants


Book Description

"The lack of discussion of the life histories of modular organisms is the weakness of this book that I most regret. . . . Modular organisms are different. " S. C. Steams: The Evolution of Life Histories (1992) Life-history theory endeavours to increase our understanding of the processe,s whereby the broad features of the life cycles of organisms, such as the timing and magnitude of reproduction, have evolved. Although reproductive traits have dominated as study objects due to their immediate importance for evolutionary success, much work has also been conducted on patterns of development, growth and senescence, as well as on the shifts in resource allocation related to these processes. The basic axiom of life-history theory is that patterns of life histories, such as reproductive traits, are subject to evolutionary explanation. This idea can be traced back at least as far as Darwin's Origin of Species (1859). In his discussion of plant domestication, Darwin wrote: "I cannot doubt that the continued selection of slight variations, either in the leaves, the flowers, or the fruit, will produce races differing from each other chiefly in these characters". Darwin was impressed by the success of plant breeders in moulding the growth and reproductive parameters of cultivated plants, and believed that natural selection could have a similar impact in natural populations.




Ecology and Evolutionary Biology of Clonal Plants


Book Description

Spontaneous self-cloning or clonality is a widespread phenomenon in the plant kingdom, and has a wide array of ecological and evolutionary implications. This volume is the outcome of an international workshop on clonal plant biology aimed at illustrating current progress and recent developments in the scientific study of clonality in plants. The first section of this book includes a collection of original research articles which demonstrate the wide variety of approaches and scientific challenges linked to clonality in plants. The topics covered in this section include ecological and evolutionary implications of sexual versus asexual propagation, including life-history evolution and sex-ratio dynamics, the importance of internal resource transport and remobilization of storage products for the invasiveness and competitiveness of clonal plants, a survey of clonal growth forms in grassland communities, and studies on the interactions between clonal plants and animals and fungi. The approaches used range from experimental studies on a broad variety of systems to mathematical modeling of clonal growth and its consequences. The second part features discussion and review papers on a diverse array of subjects, ranging from developmental considerations of clonality, principles of selection and evolution in clonal plants, a survey of clonality in algae, to potential implications of clonality for plant mating, and beyond. This part of the volume aims at presenting novel ideas and hypotheses, and at summarizing existing knowledge in previously under-researched areas, thereby providing directions for future research initiatives. This book captures ongoing cutting-edge research in the field of clonal plant ecology and evolution. It is directed to anyone from the undergraduate to specialist level who is interested in the biology of the intriguing phenomenon of asexual propagation in plants.




Functional Biology of Clonal Animals


Book Description

Clonal animals, that is those that are genetically identical, are of great importance in biology. The supposed evolutionary advantages of sexual versus asexual reproduction are one of the central paradoxes of current evolutionary theory. The evolved strategy of asexual reproduction includes a large number of diverse species in many different groups, for example aphids, guppies, planktonic rotifers and others.




Comparative Ecology of Microorganisms and Macroorganisms


Book Description

The most important feature of the modern synthetic theory of evolution is its foundation upon a great variety of biological disciplines. -G. L. STEBBINS, 1968, p. 17 This book is written with the goal of presenting ecologically significant anal ogies between the biology of microorganisms and macroorganisms. I consider such parallels to be important for two reasons. First, they serve to emphasize that however diverse life may be, there are common themes at the ecological level (not to mention other levels). Second, research done with either microbes or macroorganisms has implications which transcend a particular field of study. Although both points may appear obvious, the fact remains that at tempts to forge a conceptual synthesiS are astonishingly meager. While unify ing concepts may not necessarily be strictly correct, they enable one to draw analogies across disciplines. New starting points are discovered as a conse quence, and new ways of looking at things emerge. The macroscopic organisms ('macroorganisms') include most represen tatives of the plant and animal kingdoms. I interpret the term 'microorganism' (microbe) literally to mean the small or microscopic forms of life, and I include in this category the bacteria, the protists (excluding the macroscopic green, brown, and red algae), and the fungi. Certain higher organisms, such as many of the nematodes, fall logically within this realm, but are not discussed at any length.







Evolution and Individuality; Beyond the Genetically Homogeneous Organism


Book Description

In the first chapter, we argue that an individual organism ought not to be defined in terms of genetic homogeneity, but rather by the evolutionary criteria of the alignment of fitness interests, the export of fitness due to interdependence for survival and reproduction, and adaptive functional organization. We consider how these concepts apply to various putative individual organisms, review the costs and benefits of intraorganismal genetic heterogeneity, and demonstrate that high relatedness is neither necessary nor sufficient for individuality. In the second chapter, we model the benefits and costs of genetic mosaicism for a long-lived tree in coevolution with a short-lived pest. We demonstrate benefits of mosaicism for trees at both the individual and population levels when somatic mutation introduces new defenses. In the third chapter, we develop a game theoretic model of the decision to reject or fuse with a potential partner in a colonial ascidian, based on weighing costs and benefits of fusion. We find that once fused, the interactions between cell lineages are cooperative in the soma, but competitive in the germline.




A Functional Biology of Parasitism


Book Description

Series Editor: Peter Calow, Department of Zoology, University of Sheffield, England The main aim of this series will be to illustrate and to explain the way organisms 'make a living' in nature. At the heart of this - their functional biology - is the way organisms acquire and then make use of resources in metabolism, movement, growth, reproduction, and so on. These processes will form the fundamental framework of all the books in the series. Each book will concentrate on a particular taxon (species, family, class or even phylum) and will bring together information on the form, physiology, ecology and evolutionary biology of the group. The aim will be not only to describe how organisms work, but also to consider why they have come to work in that way. By concentration on taxa which are well known, it is hoped that the series will not only illustrate the success of selection, but also show the constraints imposed upon it by the physiological, morphological and developmental limitations of the groups. Another important feature of the series will be its organismic orientation. Each book will emphasize the importance of functional integration in the day to-day lives and the evolution of organisms. This is crucial since, though it may be true that organisms can be considered as collections of gene determined traits, they nevertheless interact with their environment as integrated wholes and it is in this context that individual traits have been subjected to natural selection and have evolved.